ISC statement

The ISC statement, in combination with a RMTCICS statement and the CICSPORT keyword on the TCPIP statement, defines to IMS Connect an Intersystem Communication (ISC) link between a local IMS system and a remote IBM® CICS® Transaction Server for z/OS® subsystem.

The ISC statement identifies the following required attributes of an ISC link:

The IDs of the partner IMS and CICS subsystems that use the link
The node name of the link
The port on which IMS Connect receives transactions and reply data from CICS
The RMTCICS statement that defines additional attributes of the ISC link, including the host name of the CICS subsystem

The required attributes that are defined by the RMTCICS statement include the host name and port of the partner CICS subsystem.

IMS Connect establishes two socket connections for each ISC parallel session: a send socket and a receive socket.

The send socket is used to send transactions and reply data to CICS via the remote CICS port that is defined on the RMTCICS statement. IMS Connect creates the send sockets when the ISC parallel session opens. IMS Connect assigns a random client name to the send socket with the three-character prefix ISC. The TCP/IP stack assigns the port number.

The receive socket is used to receive transactions, replies, and commands from CICS. Again, the receive sockets are created when the parallel session is opened. IMS Connect assigns a random client name that starts with ISC. The port number of the receive socket is defined by the CICSPORT keyword on the ISC statement. The port that CICS uses to send the data is assigned by the TCP/IP stack that the CICS subsystem uses.

ISC statement syntax

ISC statement parameters

CICSAPPL=

For an ISC TCP/IP connection to a CICS subsystem, this value must match the value specified by CICS on the APPLID= parameter of the DFHSIT macro definition in the remote CICS subsystem.

This parameter is required.

CICSNETID

For an ISC TCP/IP connection to a CICS subsystem, this NETWORK ID value is either the VTAM® NETID or the UOWNETQL= parameter of the DFHSIT macro definition in the remote CICS subsystem.

The CICSNETID value must match the remote system NETWORK ID.

This parameter is optional. When not specified, the NETWORKID value is derived from the VTAM NETID of the local IMS.

CICSPORT=

For ISC links to remote CICS subsystems, the local port that this ISC link uses. This value must match a port number defined on a CICSPORT parameter in the TCPIP configuration statement of this IMS Connect instance.

This parameter is required.

Multiple ISC statements can specify the same port number on the CICSPORT parameter if and only if they also specify the same local IMS system on the LCLIMS parameter. However, if the ISC statements specify the same CICSAPPL value, the CICSPORT values must be unique. Otherwise, IMS Connect issues an error message and abends on startup.

IMS Connect issues an error message and abends on startup in the following circumstances:

The same port number is specified on the CICSPORT parameters of two or more ISC statements that do not specify the same IMS system on the LCLIMS parameter.
The CICSPORT parameter specifies a port number that is not defined on a CICSPORT parameter of the TCPIP configuration statement.

ID=

A unique ID for this ISC statement.

The name must start with an alphabetic character and can be 1 - 8 alphanumeric characters in length.

The name must be unique within the IMS Connect configuration member. If this parameter is not unique, IMS Connect issues an error message and abends on startup.

This parameter is required.

IMSPLEX=()

Enables IMSplex communications between IMS Connect and ISC. IMSplex communications are managed by the Structured Call Interface (SCI) component of the IMS Common Service Layer (CSL).

If another IMSPLEX statement in this member of the IMS PROCLIB data set already joins IMS Connect to the IMSplex in which the ISC-enabled IMS system is a member, then this IMSPLEX substatement is optional; however, at least one IMSPLEX statement must be specified in the HWSCFGxx member of the IMS PROCLIB data set to enable IMSplex communications between this IMS Connect instance and ISC.

If an IMSPLEX substatement is not included on the ISC statement, and more than one IMSPLEX statement is specified elsewhere in this HWSCFGxx member of the IMS PROCLIB data set, IMS Connect uses the first IMSPLEX statement in the HWSCFGxx member of the IMS PROCLIB data set for communications between IMS Connect and ISC.

MEMBER=

A 1- to 8-character alphanumeric name that identifies IMS Connect in the IMSplex. The name must start with an alphabetic character. IMS Connect registers this name with SCI.

For dynamic ISC terminals that are defined to IMS by a logon descriptor, this name must match the name specified on the LCLICON parameter of the logon descriptor in either the DFSDSCMx or DFSDSCTy PROCLIB member of the local IMS system.

For ISC terminals that are statically defined to IMS by a TERMINAL system definition macro, this name must match the iconname value specified on the ISCTCPIP parameter of the DFSDCxxx PROCLIB member of the local IMS system.

Note: An IMS Connect instance can register only a single name in an IMSplex. If the same IMSplex name is specified on two or more TMEMBER parameters in the HWSCFGxx member of the IMS PROCLIB data set, then the same IMS Connect name must be specified on each of the corresponding MEMBER parameters. If the MEMBER parameters differ on two or more IMSplex statements that specify the same IMSplex name, IMS Connect issues an error message and abends on startup.

TMEMBER=

The name of the IMSplex that IMS Connect is joining, as specified on the IMSPLEX(NAME=) statement of the CSLSIxxx member of the IMS PROCLIB data set of the SCI instance that is managing communications between IMS Connect and the IMSplex.

Restriction: The name specified on the TMEMBER parameter cannot be the same as a name specified on the ID parameter of any DATASTORE statement.

LCLIMS=

This is the IMS ID of the local IMS system as registered with SCI in the IMSplex. It is a 1- to 8-character alphanumeric name that begins with an alphabetic character.

The values of the NODE keyword and the LCLIMS keyword must create a unique pair among all ISC statements in the IMS Connect configuration member.

You can determine the IMS IDs of the IMS systems that are registered with SCI by issuing the QUERY IMSPLEX command in the local IMSplex.

This parameter is required.

NODE=

The name of this ISC node as defined to the local IMS.

For static terminal definitions, the value specified on the NODE parameter must match both the NAME parameter on the TERMINAL system definition macro and the nodename value of the ISCTCPIP parameter on the DFSDCxxx PROCLIB member.

For dynamic terminal definitions, the value specified on the NODE parameter is used only in the /OPNDST command when a user initiates a new session with the CICS subsystem specified on the CICSAPPL parameter.

The values of the NODE keyword and the LCLIMS keyword must create a unique pair among all ISC statements in the IMS Connect configuration member.

This parameter is required.

RMTCICS=

For a connection to a CICS subsystem, specifies the ID of the RMTCICS statement that defines the TCP/IP connection that this ISC link uses to communicate with a remote CICS subsystem. This value must match the value of the ID= parameter of a RMTCICS statement that is defined in the IMS Connect configuration PROCLIB member.

When multiple ISC links connect to the same CICS subsystem, they can use the same TCP/IP connection definition or they can use separately defined TCP/IP connections. ISC links that use the same TCP/IP connection must specify the same ID on the RMTCICS parameter. ISC links that use separately defined TCP/IP connections to the same CICS subsystem must specify different IDs on the RMTCICS parameter; however the different RMTCICS statements that each ISC statement references must specify the same host name or IP address and port number.

This parameter is required.